2차전지 소재용 Al박판과 Ni박판의 연속파형 파이버 레이저 용접 특성 비교

Abstract

As the modern industrial society develops, the society which uses a large quantity of fossil fuel has a risk in social stability because it depends on crude oil in politically unstable regions. From this reason, Some countries in the world has reinforced a restriction on the mileage of a car to limit the emission of greenhouse gas caused by the use of fossil fuel. Since the price of fossil fuel has been increased and the environmental pollution may occur in a long term, the development of Green Car has been actively in progress focusing on people's concern on the discovery of a power source for replacing the fossil fuel. Especially, among Green Cars, Hybrid and Electric cars have been made for practical use as for a plan to resolve problems of the environmental pollution by fossil fuel and the depletion of resources. Since a driving motor and a high capacity battery are very important core elements of Hybrid and Electric cars, many concerns have focused on the development and its performance improvement of the secondary battery which is the power source in the battery industry. In this study, by using 10kW continuous wave fiber laser, we conducted experiments in a laser overlap joint welding based on pure aluminum and nickel materials used in the Lithium secondary battery. The laser overlap joint welding is conducted for ten sheets with thickness of each specimen as 100㎛ and beam travel speeds from 4m/min to 10m/min with the step of 2m/min, and experiments are conducted for the process variables with laser powers of 1800W, 2000W, and 2200W. As a result from experiments, ten sheets of both Aluminum and Nickel specimens go through a penetration welding at 2200W with beam travel speeds from 4m/min to 10m/min. For the process variable which shows the highest tensile strength in Aluminum, the highest tensile strength is obtained as 25.32MPa at 1800W with a beam travel speed of 10m/min, and for Nickel, among those process variables, the highest tensile strength is obtained as 189.34MPa at 2200W with a beam travel speed of 10m/min. Although many blow holes occur at the welding part microstructure of Aluminum, the blow defects are decrease at the center of the welding part as the beam travel speed for each process variable is increased. The study should be proceeded further on methods for eliminating defects of Aluminum laser welding.